It is known from European Patent Application Ser. No. 91111-143.3 (Publication No. 0466031 A2) that the immune system of aquatic animals can be stimulated through the administering of an effective amount of a yeast cell wall glucan. It is further known that the effect of vaccines on such aquatic animals can be enhanced by the administering of an effective amount of such yeast cell wall glucan along with the vaccine antigens.
Such glucan compositions are particulate glucans such as that derived from the yeast Saccharomyces cerevisiae. Such particulate glucans are macromolecular and are comprised of a chain of glucose units linked by β-(1-3)- and β-(1-6)-linkages, said glucan being a branched β-(1,3)-glucan having β-(1,3)-linked and β-(1,6)-linked chains therein.
Such particulate glucans are provided by KS Biotec-Mackzymal under the brand “MacroGard” and are potent activators of the macrophage/monocyte cell series. Thus such particulate glucans have a profound effect on the immune system.
While the particulate glucan derived from Saccharomyces cerevisiae is recognized to have a variety of beneficial effects on fish and other animals, the use of the glucan in the particulate and thus insoluble form is limited.
In addition it is now believed that the presence of β-(1-3)-branches contribute to the desired pharmaceutical benefits to be obtained from particulate glucan.
Accordingly a system whereby the β-(1-3)-linked branches are made more readily available in the glucan would be highly desirable.